Branched polyolefin synthesis

ABSTRACT

The present invention relates to a process for the free radical initiated polymerization of unsaturated species characterized by the use of compound of Formula (I) as chain transfer agents, wherein X is selected from hydrogen; CN; optionally substituted aryl; COOH; COOR; C(O)NHR 6 ; C(O)NR 7 R 8 ; and halogen; Q is selected from COOR 1 ; CN; and C(O)NR 7 R 8 ; Y is selected from hydrogen; C 1  to C 6  alkyl; C 1  to C 6  alkyl substituted with one or more substituents selected from hydroxy, amino, C 1  to C 6  alkoxy, C 1  to C 6  alkoxycarbonyl, halogen, CN and optionally substituted aryl; C 1  to C 6  alkenyl; and C 1  to C 6  alkynyl; Z is selected from COOR 2 ; CN; and optionally substituted aryl; R 3  and R 4  may be the same or different and are selected from hydrogen, C 1  to C 4  alkyl and halogen; or R 3  and R 4  together with the carbon atom to which they are attached form part of a carbocyclic or heterocyclic ring structure; R is selected from C 1  to C 18  alkyl; C 1  to C 12  alkyl substituted with one or more substituents selected from hydroxy, amino, C 1  to C 6  alkoxy, phenyl, halogen, NCO, CN, and COOR 5 ; R 1  and R 2  may be the same or different and are selected from C 1  to C 18  alkyl; C 1  to C 12  alkyl substituted with one or more substituents selected from hydroxy, C 1  to C 6  acyloxy, C 1  to C 6  alkoxy, amino, halogen, Si(R 9 ) 3 , Si(OR 9 ) 3 , optionally substituted aryl, CN and NCO; R 5  is selected from hydrogen and C 1  to C 6  alkyl; R 6  is selected from hydrogen and C 1  to C 18  alkyl; R 7  and R 8  may be the same or different and are selected from C 1  to C 18  alkyl; and R 9  is selected from C 1  to C 18  alkyl; C 1  to C 18  cycloalkyl; and optionally substituted aryl.

[0001] This invention relates to processes for radical-initiatedpolymerization of unsaturated species and for the control of molecularweight of the polymers produced from such processes. Polymers of lowmolecular weight, or oligomers, are important as precursors in producingother polymeric materials and such polymers have been found to be usefulin a variety of products, for example, in the production of high solids(low VOC) surface coatings, in adhesives and as plasticizers inpolymeric composites.

[0002] In conventional polymerization practice, the manufacture ofoligomers requires the use of an initiator which acts as a free radicalsource, and of a chain transfer agent. The chain transfer agent controlsthe molecular weight of the polymer by reacting with the propagatingpolymer radical to terminate its growth. It then initiates a new polymerchain thus transferring the growth process from one discrete polymermolecule to another discrete polymer molecule.

[0003] The most commonly used chain transfer agents are alkanethiols,which normally are associated with an objectionable odour and lead to awide distribution of molecular weight with certain monomers. Also, theresidual thiols and the end thio-ether linkage of the polymers may havean adverse effect on the properties of the ultimate product from thepolymer.

[0004] The present invention helps overcome the disadvantages ofpolymerizations regulated with thiols by using alternativepolymerization regulators. These regulators have good stability andshelf life while maintaining many of the advantages over thiols. In themajority of cases, the materials that are part of the present processpresent a different range of chain transfer activities, allowing moreopportunity for an optimal process to be selected for a givenpolymerization system of monomers and polymerization conditions. Thechain transfer constant that a given regulator possesses is an importantconsideration in selecting the optimum process for producing lowmolecular weight polymers.

[0005] This invention provides a process for the free radicalpolymerization of unsaturated species to provide polymers with lowermolecular weight and narrower polydispersity characterized by the use ofcompounds of Formula (I) as chain transfer agents.

[0006] wherein

[0007] X is selected from hydrogen; CN; optionally substituted aryl;COOH; COOR; C(O)NHR⁶; C(O)NR⁷R⁸; and halogen;

[0008] Q is selected from COOR¹; CN; and C(O)NR⁷R⁸;

[0009] Y is selected from hydrogen; C₁ to C₆ alkyl; C₁ to C₆ alkylsubstituted with one or more substituents selected from hydroxy, amino,C₁ to C₆ alkoxy, C₁ to C₆ alkoxycarbonyl, halogen, CN and optionallysubstituted aryl; C₁ to C₆ alkenyl; and C₁ to C₆ alkynyl;

[0010] Z is selected from COOR²; CN; and optionally substituted aryl;

[0011] R³ and R⁴ may be the same or different and are selected fromhydrogen, C₁ to C₄ alkyl and halogen; or R₃ and R⁴ together with thecarbon atom to which they are attached form part of a carbocyclic orheterocyclic ring structure;

[0012] R is selected from C₁ to C₁₈ alkyl; C₁ to C₁₂ alkyl substitutedwith one or more substituents selected from hydroxy, amino, C₁ to C₆alkoxy, phenyl, halogen, NCO, CN, and COOR⁵;

[0013] R¹ and R² may be the same or different and are selected from C₁to C₁₈ alkyl; C₁ to C₁₂ alkyl substituted with one or more substituentsselected from hydroxy, C₁ to C₆ acyloxy, C₁ to C₆ alkoxy, amino,halogen, Si(R⁹)₃, Si(OR⁹)₃, optionally substituted aryl, CN and NCO;

[0014] R⁵ is selected from hydrogen and C₁ to C₆ alkyl;

[0015] R⁶ is selected from hydrogen and C₁ to C₁₈ alkyl;

[0016] R⁷ and R⁸ may be the same or different and are selected from C₁to C₁₈ alkyl; and

[0017] R⁹ is selected from C₁ to C₁₈ alkyl; C₁ to C₁₈ cycloalkyl; andoptionally substituted aryl.

[0018] A preferred group of compounds of Formula I are the malonateswith Q=COOR¹ and Z=COOR² having the Formula (IA):

[0019] wherein:

[0020] X is selected from hydrogen; CN; optionally substituted aryl;COOH; COOR; C(O)NHR⁶; C(O)NR⁷R⁸; and halogen;

[0021] Y is selected from hydrogen; C₁ to C₆ alkyl; C₁ to C₆ alkylsubstituted with one or more substituents selected from hydroxy, amino,C₁ to C₆ alkoxy, C₁ to C₆ alkoxycarbonyl, halogen, CN, optionallysubstituted aryl; C₁ to C₆ alkenyl; and C₁ to C₆ alkynyl;

[0022] R¹ and R² may be the same or different and are selected from C₁to C₁₈ alkyl; C₁ to C₁₂ alkyl substituted with a substituent selectedfrom hydroxy, C₁ to C₆ acyloxy, C₁ to C₆ alkoxy, amino, halogen,optionally substituted aryl, CN and NCO;

[0023] R³ and R⁴ may be the same or different and are selected fromhydrogen; C₁ to C₄ alkyl; and halogen; and

[0024] R, R⁶, R⁷ and R⁸ are as defined above.

[0025] Another preferred group of compounds which possess high chaintransfer activities are the compounds of Formula (IB) where Q=COOR¹ andZ is optionally substituted aryl:

[0026] wherein:

[0027] X, Y, R¹, R³ and R⁴ are as defined above; and

[0028] Z is optionally substituted aryl.

[0029] The term “optionally substituted aryl” is used herein to mean anaromatic carbocyclic group which may or may not be substituted with oneor more substituents that do not interfere with the polymerizationprocess. Such substituents include alkyl, hydroxyalkyl, aminoalkyl,carboxylic acid, ester, acyloxy, amide, nitrile, haloalkyl, alkoxy,phosphonate, sulfonate, silyl or silyloxy groups.

[0030] Preferred aryl groups are phenyl or naphthyl groups.

[0031] When X is halogen, chlorine or bromine are preferred.

[0032] When R³or R⁴ is halogen, chlorine or fluorine are preferred.

[0033] The following compounds of Formula I are novel and form part ofthe invention:

[0034] ethyl 2,4-bis(ethoxycarbonyl)-2-methyl-4-pentenoate;

[0035] ethyl 2,4-bis(ethoxycarbonyl)-2-ethylpentenoate;

[0036] ethyl 2-benzyl-2,4-bis(ethoxycarbonyl-4-pentenoate;

[0037] ethyl 2-ethoxycarbonyl-2-methyl-4-phenyl-4-pentenoate;

[0038] ethyl2-ethoxycarbonyl-2,3-dimethyl-4-(t-butoxycarbonyl)-4-pentenoate; and

[0039] ethyl 2-phenyl-4-(t-butoxycarbonyl)-4-pentenoate.

[0040] The process of this invention uses the compounds of Formula (I)as alternatives to thiols or other chain transfer agents for the controlof molecular weight The process of this invention may be operated in asimilar manner to conventional processes using thiols. The compounds ofFormula I can be prepared easily from inexpensive starting materials.Unlike thiols, they do not, in general, possess an objectionable odour.

[0041] The materials of this invention exhibit unexpectedly good chaintransfer activities in general. For example, compound ethyl2,4-bis(ethoxycarbonyl)-2-methyl-4-pentenoate (Ib) of this inventionpossesses significantly higher activity when compared with the methyl4-methoxycarbonyl-2,2-dimethyl-4-pentenoate (MMA dimer or dimethyl2,2-dimethyl-4methylene glutarate) (refer to Table 5) in methylmethacrylate, acrylate and styrene polymerizations. The advantages ofthis invention will become more apparent by referring to theillustrative non-limiting examples shown below.

[0042] Preparation of Chain Transfer Agents

[0043] The allylic malonate derivatives [Formula (IA)] are synthesizedin good to excellent yield in a one-step reaction between thecorresponding allylic halides (II) and malonates (IIIA). The reaction iscarried out in the presence of base and solvent Acetonitrile,N,N-dimethylformamide (DMF), dried THF or diethyl ether are suitablesolvents. Although many (inorganic and organic) bases are suitable,sodium hydride, sodium alkoxide, sodamide, potassium alkoxides arepreferred bases. The use of sodium hydride is found to provide betterresults than sodium alkoxide for the synthesis of these types ofcompounds.

[0044] Similarly, the allylic compounds of Formula IB. [e.g., compound(Ii)] can be synthesized in good yield in a one-step reaction betweenthe corresponding allylic halide (II) and arylacetate (IIIB). Thereaction is carried out in the presence of base and solvent.

[0045] Typical compounds (Ia & Ib) used in the process of this inventionand their preparation are further illustrated by the followingnon-limiting preparative examples.

Preparative Example 1

[0046] Ethyl 2,4-bis(ethoxycarbonyl)-4-pentenoate (Ia)

[0047] [Formula (IA), X=COOCH₂CH₃; Y=R³=R⁴=H; R¹=R²=CH₂CH₃]. [Typicalprocedure].

[0048] To a suspension of sodium hydride (80% dispersion in oil, 0.36 g,12 mmol) in acetonitile (10 mL), was added diethyl malonate (1.60 g, 10mmol). The resulting suspension was allowed to stir at room temperaturefor 15 minutes. A solution of ethyl α-(bromomethyl)acrylate [obtainedfrom a modified procedure of S. E. Drewes, G. Loizou and G. H. P. Roos,Synthetic Communications, 1987, 17(3), 291-298) (1.93 g, 10 mmol) inacetonitrile (5 mL) was then added slowly to the above suspension.Stirring was maintained for 2 hours and then the reaction mixture waspoured into water, and extracted (3x) with diethyl ether. The extractswere combined and dried over anhydrous Na₂SO₄, filtered and evaporatedto dryness. Distillation of the crude product under reduced pressuregave (Ia) as a colourless liquid (b.p.˜140° C./0.1 mmHg) (1.90 g, ˜70%).¹H-NMR (CDCl₃) δ(ppm) 1.21 (t, 6H), 1.25 (t, 3H), 2.85 (d, 2H), 3.67 (t,1H), 4.15 (q, 4H), 4.20 (q, 2H), 5.60 (br. s, 1H) and 6.18 (br. s, 1H).¹³C-NMR (CDCl₃) δ(ppm) 13.98, 31.34, 50.76, 60.81, 61.37, 127.56,136.68, 166.38 and 168.67.

Preparative Example 2

[0049] Ethyl 2,4-bis(ethoxycarbonyl)-2-methyl-4-pentenoate (Ib)

[0050] [Formula (IA), X=COOCH₂CH₃; Y=CH₃; R³=R⁴=H; R¹=R²=CH₂CH₃]. Thiscompound was prepared using a similar procedure to that described above.Pure ethyl 2,4-bis(ethoxycarbonyl)-2-methyl-4-pentenoate (lb) wasobtained (60% yield) after column chromatography on silica-gel (diethylether: n-hexane 1:4 as eluent). ¹H-NMR (CDCl₃) δ(ppm) 1.20 (t, 6H), 1.25(t, 3H), 1.33 (s, 3H), 2.95 (s, 2H), 4.15 (m, 6H), 5.56 (br. s, 1H) and6.22 (br. s, 1H). ¹³C-NMR (CDCl₃) δ(ppm) 13.91, 14.06, 35.98, 53.88,60.78, 61.23, 128.61, 136.29, 166.67 and 171.57.

Preparative Example 3

[0051] Ethyl 2,4-bis(ethoxycarbonyl)-2-ethyl-4-pentenoate (Ic)

[0052] [Formula (IA), X=COOCH₂CH₃; Y=CH₂CH₃; R³=R⁴=H; R¹R²=CH₂CH₃].

[0053] This compound was prepared in -80% yield using a similarprocedure to that described in Example 1. ¹H-NMR (CDCl₃) δ(ppm) 0.85 (t,3H), 1.20 (t, 6H), 1.30 (t, 31), 1.85 (q, 2H), 2.95 (s, 211), 4.15 (m,6H), 5.58 (br. s, 1H) and 6.25 (br. s, 1H). ¹³C-NMR (CDCl₃) δ(ppm) 8.58,14.06, 14.16, 25.46, 32.98, 58.32, 60.89, 61.15, 128.42, 136.53, 167.05and 171.09.

Preparative Example 4

[0054] Ethyl 2-benzyl-2,4-bis(ethoxycarbonyl)-4-pentenoate (Id)

[0055] [Formula (IA), X=COOCH₂CH₃; Y=CH₂C₆H₅; R³=R⁴=H; R¹=R²=CH₂CH₃].

[0056] This compound was prepared by a procedure similar to Example 1,using diethyl benzylmalonate as the staring material; the product wasisolated in 76% yield as a colourless syrup. ¹H-NMR (CDCl₃) δ(ppm) 1.20(t, 6H), 1.30 (t, 3H), 2.95 (s, 2H), 3.25 (s, 2H), 4.15 (m, 6H), 5.65(br. s, 1H), 6.25 (br. s, 1H) and 7.20 (m, 5H). ¹³C-NMR (CDCl₃) δ(ppm)13.82, 14.11, 30.40, 39.63, 43.30, 58.75, 60.84, 61.20, 126.87, 128.11,128.55, 130.08, 167.40 and 170.56.

Preparative Example 5

[0057] Ethyl 4-chloro-2-ethoxycarbonyl-2-methyl-4-pentenoate (Ie)

[0058] [Formula (IA), X=Cl; Y=CH₃; R³=R⁴=H; R¹=R²=CH₂CH₃].

[0059] To a suspension of sodium hydride (25.2 g, 0.84 moles, 80%dispersion in oil) and diethyl methylmalonate (104.5 g, 0.60 moles) inacetonitrile (500 mL), a solution of 2,3-dichloropropene (66.6 g, 0.60moles) in acetonitrile (100 mL) was added slowly over 20 minutes withstirring at room temperature. The resulting mixture was allowed to stirat room temperature overnight. Water (250 mL) was added, and the mixtureextracted three times with diethyl ether (200 mL×3). The combinedorganic layers were washed successively with water (200 mL) and brine(200 mL), they were then dried over anhydrous MgSO₄. After removal ofthe organic solvent, distillation of the crude product under reducedpressure afforded the product (Ie) as a colourless liquid (91.6 g, 61.5%yield), b.p. 77-78° C. (0.1 mmHg). ¹H-NMR (CDCl₃) δ(ppm) 1.22 (t, 6H),1.42 (s, 3H), 3.00 (s, 2H), 4.18 (q, 4H), 5.20 (s, 1H) and 5.30 (s, 1H).

Preparative Example 6

[0060] Ethyl 2-ethoxy carbonyl-4-phenyl-4-pentenoate (If)

[0061] [Formula (IA), X=Phenyl; Y=R³=R⁴=H; R¹=R²=CH₂CH₃].

[0062] This compound was prepared in ˜20% yield (not optimized)according to a similar procedure to that described in Example 1. Thereaction was carried out between α-(bromomethyl)styrene [obtained fromthe reaction of α-methylstyrene and N-bromosuccmimide in carbontetrachloride according to the published procedure by H. Pines, H. Aluland M. Kolobielski, J. Org. Chem., 1957, 2, 1113-1114] and diethylmalonate in the presence of sodium hydride (1 eq.). ¹H-NMR (CDCl₃)δ(ppm) 1.25 (t, 6H), 3.10 (d, 21), 3.50 (t, 1H), 4.17 (q, 411), 5.15(br. s, 1H), 5.35 (br. s, 1H) and 7.35 (m, 5H).

Preparative Example 7

[0063] Ethyl 2-ethoxycarbonyl-2-methyl-4-phenyl-4-pentenoate (Ig)

[0064] [Formula (IA), X=Phenyl; Y=CH₃; R³=R⁴=H; R¹=R²=CH₂CH₃].

[0065] This compound was prepared in ˜60% yield by reactingα-(bromomethyl)styrene [obtained by method of H. Pines, H. Alul, M.Kolobielski, J. Org. Chem., p. 1113 (1957)] and diethyl methylmalonatein the presence of sodium hydride (2 eq.) in acetonitrile solvent ¹H-NMR(CDCl₃) δ(ppm) 1.10 (t, 6H), 1.30 (s, 3H), 3.18 (s, 2H), 3.90 (m, 4H),5.10 (br. s, 1H), 5.27 (br. s, 1H) and 7.30 (m, 5H).

Preparative Example 8

[0066]Ethyl-2-ethoxycarbonyl-2,3-dimethyl-4-(t-butoxycarbonyl)-4-pentenoate(Ih)

[0067] [Formula (IA), X=COOC(CH₃)₃; Y=CH₃; R³=H; R⁴=CH₃; R¹R²=CH₂CH₃].

[0068] The starting material, t-butyl(Z)-2-bromomethyl-2-butenoate, wasprepared via literature procedures [H. Hoffmann and J. Rabe, HelveticaChimica. Acta, 67(2), p. 413 (1984)].

[0069] A stirred solution of diethyl methylmalonate (1.5 g, 8.6 mmol) indistilled TEF was cooled to −5° C. and sodium hydride (0.52 g) addedportionwise. The resultant suspension was stirred below 0° C. for anhour, then t-butyl (Z)-2-bromomethyl-2-butenoate added dropwise. Themixdue was stirred below 0° C. for a further two hours before beingallowed to warm to room temperature and stirred overnight. Solvent wasremoved under reduced pressure, water added and the product extractedwith ether (3×50 ml), and the combined organic layers dried overanhydrous magnesium sulphate. Upon removal of ether under reducedpressure, a pale yellow oil was obtained (2.02 g, 72%). ¹H-NMR spectrumrevealed the presence of two isomers in a ratio of 4:1, with thepreferred isomer being the major product (Ih). Column chromatography onsilica gel (9:1, pet. spirit 40-60° C.:ethyl acetate) gave slightseparation of the two isomers. The fraction containing the highest levelof ethyl-2-ethoxycarbonyl-2,3-dimethyl-4-(t-butoxycarbonyl)pent-4-enoate (Ih) was used for the following spectroscopic data. ¹H-NMR(CDCl₃) δ(ppm): 6.25, s, 1H; 5.55, s, 1H; 4.2, m, 4H; 3.7, q, 1H;1.2-1.6, m, 21H. ¹³C-NMR (CDCl₃) δ(ppm): 171.7, 171.2, 166.6, 143.5,125.2, 80.5, 61.1, 57.5, 36.7, 28.0, 17.5, 17.0, 14.0, 13.9.

Preparative Example 9

[0070] Ethyl 2-phenyl-4-(t-butoxycarbonyl)-4-pentenoate (Ii)

[0071] [Formula (IB), X=COOC(CH₃)₃; Y=R³=R⁴=H; R¹=CH₂CH₃; Z=phenyl]

[0072] The starting allylic bromide material, 1-butyl2-(bromomethyl)propenoate was prepared via a modified procedure of S. E.Drewes, G. Loizou and G. H. P. Roos, Synthetic Communications, 1987,17(3) 291-298 using 1-butyl acrylate.

[0073] Ethyl phenylacetate (6.66 g, 40.6 mmol) was dissolved in dry TBF(20 mL) and sodium hydride (1.09 g, 36.5 mmol) added portionwise. Theresulting suspension was stirred at room temperature for 30 minutes thencooled on ice while t-butyl 2-(bromomethyl)propenoate (4.49 g, 20.3mmol) was added dropwise under nitrogen atmosphere. On completion of theaddition, the reaction mixture was allowed to reach room temperaturethen heated under reflux for 8 hours. The THF solvent was removed underreduced pressure, water added and the product mixture extracted withdiethyl ether (3×50 mL). After removal of organic solvent, the excessethyl phenylacetate was removed by vacuum distillation and the residuewas chromatographed on a silica-gel column using 5% ethyl acetate inpetroleum spirit as eluent. The pure product (Ii) was obtained as a verypale yellowish liquid (2.5 g, 41%). ¹H-NMR (CDCl₃) δ(ppm): 1.10, t, 3H;1.45, s, 9H; 2.65, dd, 1H; 3.00, dd, 1H; 3.85, dd, 1H; 4.10, m, 2H;5.35, s, 1H; 6.00, s, 1H; 7.25, s, 5H.

[0074] Operation of the Process

[0075] The process of this invention may be adopted by the users ofconventional processes using thiols with little change to reactionconditions other than the substitution of the appropriate quantity ofcompound of general Formula (I) for the thiol. The proportion ofcompound of Formula (I) used may be in the range of 0.01 to 30 molepercent based on total monomer, with a preferred range of 0.1 to 10 molepercent.

[0076] The process may be operated at any of the reaction conditionsappropriate to free radical polymerization, ie., temperatures from −100°C. to 200° C. and pressures from below atmospheric to substantiallyabove atmospheric.

[0077] The polymerization process can be carried out in bulk, solution,emulsion, suspension or other conventional polymerization modes. Sourceof radicals for polymerizations are well known in the art and theyinclude α,α′-azobisisobutyronitrile, 4,4′-azobis(4-cyanovaleric acid),2,2′-azobis(2,4-dimethylpentanenitrile), benzoyl peroxide, t-butylperoxybenzoate, ammonium persulfate, potassium persulfate.

[0078] Any unsaturated monomers susceptible to free radicalpolymerization may be used although it should be noted that the chaintransfer constant will vary with the monomer used. Suitable unsaturatedmonomers include acrylic esters, methacrylic esters, vinyl esters, vinylaromatics, unsaturated or polyunsaturated hydrocarbons, or mixtures ofthese. Examples of these monomers are methyl acrylate, ethyl acrylate,butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethylmethacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, vinylacetate, styrene, p-chloromethylstyrene, 2-vinylpyridine,4-vinylpyridine, N-vinylpyrrolidone, vinyl halides of the formulaCH₂═CHX where X is Cl or F, vinylidene halides of the formula CH₂═CX₂wherein X is independently Cl or F, vinyl ethers CH₂═CHOR where R isalkyl, and allyl monomers such as allyl ethers, allyl carbonates ordiallyl carbonates.

[0079] Compounds of general Formula (I) used in the process of thisinvention display an unexpected high activity in controlling molecularweight in polymerization reactions and have chain transfer constantsthat may be superior to those of thiols, particularly with styrene andacrylates. Their activity is such that their chain transfer constantscan approach the optimum values of 1.0 for batch polymerizations andthis activity is not as highly dependent as that of thiols on thestructure of the propagating radical.

[0080] The process is applicable to the manufacture of syntheticrubbers, and other polymer formulations where reduced molecular weightaids processing and improves properties. The process can also be used toproduce low molecular weight polymers, oligomers, macromonomers andfunctional polymers for a variety of applications such as high-solidssurface coatings, paints, and adhesives. Furthermore, the process can beused to enable better control over the polymerization kinetics, e.g.,delaying the onset of gelation in cross-linking systems.

[0081] The operation of this process is demonstrated by the followingnon-limiting examples. In these examples molecular weight measurementswere performed on a Waters Associates liquid chromatograph equipped withdifferential refractometer and six μ-styragel columns of 10⁶, 10⁵, 10⁴,10³, 500 and 100 Å pore size. Tetrahydrofuran solvent was used at a flowrate of 1 mL/min. Results were derived by comparison with polystyrenestandards using the Chromatix GPC-1 program.

[0082] The conversions were determined from the mass of the polymersisolated after precipitation in solvents where appropriate or afterremoval of all the volatiles in vacuo, and after subtracting the mass ofthe chain transfer agent.

Example 1: Polymerization of Methyl Methacrylate

[0083] α,α′-Azobisisobutyronitrile (23.4 mg) was dissolved in freshlydistilled inhibitor-free methyl methacrylate (MMA) (25 mL). Aliquots (4mL) were removed and added to ampoules containing weighed amounts of theallylic chain transfer agent of Formula (I). The contents of the ampoulewere either degassed by three freeze-evacuate-thaw cycles and sealedunder vacuum or by bubbling nitrogen through the solution. The mixtureswere then polymerized at 60 ° C. for one hour. The contents of theampoules were then added dropwise to methanol and the precipitatedpolymers were collected and dried in a vacuum oven to constant weight Asmall portion of each polymer was examined by gel-permeationchromatography (GPC) to determine its molecular weight. TABLE 1Molecular Weight and Conversions for Methyl Methacrylate PolymerizationsCarried Out in the Presence of Chain Transfer Agents (CTA) Temp. Time10³[CTA]/ % Entry CTA (° C.) (hr.) [Monomer] Conv. M_(n) ^(#) 1 Ia 601.00 0.00 15.80 327160 2 Ia 60 1.00 10.20 14.70 287300 3 Ia 60 1.0022.80 13.30 253630 4 Ib 60 1.00 0.00 14.95 159200 5 Ib 60 1.00 16.8013.35 104100 6 Ib 60 1.00 31.30 12.80 89900 7 Ib 60 1.00 68.30 11.2058700 8 Ic 60 1.00 0.00 16.30 254350 9 Ic 60 1.00 14.32 12.10 195900 10Ic 60 1.00 28.37 9.95 190150 11 Ic 60 1.00 56.73 8.30 153150 12 If 601.00 0.00 14.72 266800 13 If 60 1.00 9.82 2.44 89000 14 If 60 1.00 19.641.30 64875 15 If 60 1.00 38.58 1.22 50800 16 Ig 60 1.00 0.00 11.49299000 17 Ig 60 1.00 9.89 4.48 113400 18 Ig 60 1.00 19.03 0.42 91990 19Ig 60 1.00 36.34 1.47 57530 20 Ii 60 1.00 0.00 12.74 248860 21 Ii 601.00 9.89 11.52 131020 22 Ii 60 1.00 18.15 11.61 100900 23 Ii 60 1.0034.50 10.30 71120

Example 2: Polymerization of Styrene

[0084] Polymerizations of styrene (Sty) were carried out similarly forthree hours at 60° C. α,α′-Azobisisobutyronitrile (21.6 mg) wasdissolved in freshly distilled styrene (50 mL). Aliquots (10 mL) wereremoved and transferred to ampoules containing weighed amounts of chaintransfer agent. After the degassing and polymerizaon, the contents ofampoules were poured into menthol and the precipitated polymers werecollected, dried, and examined as before. TABLE 2 Molecular Weight andConversions for Styrene Polymerizations Carried Out in the Presence ofAllylic Malonate Chain Transfer Agents and MMA Dimer (Methyl4-methoxycarbonyl-2, 2-dimethyl-4-pentenoate) Temp. Time 10³[CTA]/ %Entry CTA (° C.) (hr.) [Monomer] Conv. M_(n) ^(#) 1 Ia 60 3.00 0.00 9.80130000 2 Ia 60 3.00 13.20 8.40 119250 3 Ia 60 3.00 26.20 9.30 114300 4Ib 60 3.00 0.00 8.30 127000 5 Ib 60 3.00 14.86 4.20 20400 6 Ib 60 3.0032.78 3.65 12500 7 Ib 60 3.00 43.11 3.20 11400 8 Ih 60 3.00 0.00 8.4103995 9 Ih 60 3.00 8.75 6.3 43755 10 Ih 60 3.00 16.90 5.8 28222 11 Ih60 3.00 30.40 5.2 18682 12 Ii 60 3.00 0.00 9.0 112525 13 Ii 60 3.00 9.018.3 102660 14 Ii 60 3.00 18.35 7.4 89260 15 Ii 60 3.00 38.69 6.5 8094016 MMA Dimer 60 3.00 0.00 10.5 120010 17 MMA Dimer 60 3.00 12.50 7.059855 18 MMA Dimer 60 3.00 25.00 5.8 41220 19 MMA Dimer 60 3.00 49.885.7 27830

Example 3: Polymerization of Acrylate Esters

[0085] Polymerizations of methyl acrylate (MA) (or ethyl acrylate, EA)were carried out using a stock solution prepared fromα,α′-azobisisobutyronitrile (6.34 mg) and distilled thiophene-freebenzene (25 mL). Aliquots (6 ml) were removed and added to ampoulescontaining freshly distilled methyl acrylate (4 mL), thiophene-freebenzene (10 mL) and weighed amounts of the activated allylic malonatechain transfer agents. After degassing, the mixtures were polymerized at60° C. for one hour; or at 80° C. for 30 minutes; or at 90° C. for 30minutes. The volatiles were then removed on rotary evaporator and thepolymers were dried in vacuo to constant weight and examined by GPC.TABLE 3 Molecular Weight and Conversions for Acrylate PolymerizationsCarried Out in the Presence of Chain Transfer Agents (CTA) Mono- Temp.Time 10³[CTA]/ % Entry mer CTA (° C.) (hr.) [Monomer] Conv. M_(n) ^(#) 1MA Ia 80 0.50 0.00 38.70 183900 2 MA Ia 80 0.50 10.00 36.60 137500 3 MAIa 80 0.50 20.60 31.90 95750 4 MA Ia 80 0.50 39.75 25.60 67400 5 EA Ib60 1.00 0.00 8.80 235,600 6 EA Ib 60 1.00 4.33 4.60 89400 7 EA Ib 601.00 5.87 3.85 53100 8 EA Ib 60 1.00 12.81 2.30 33500 9 MA Ie 60 1.000.00 26.3 493150 10 MA Ie 60 1.00 3.73 25.3 467300 11 MA Ie 60 1.0014.67 21.8 362400 12 MA If 60 1.00 0.00 28.2 388450 13 MA If 60 1.009.43 ˜0.0 31455 14 MA If 60 1.00 20.61 ˜0.0 8140 15 MA If 60 1.00 34.18˜0.0 5810 16 MA If 80 0.50 0.00 46.0 133300 17 MA If 80 0.50 8.70 0.3922630 18 MA If 80 0.50 18.10 1.60 11540 19 MA If 80 0.50 34.44 ˜0.0 437520 MA Ig 60 1.00 0.00 21.44 657800 21 MA Ig 60 1.00 8.84 0.47 13260 22MA Ig 60 1.00 21.32 0.14 4885 23 MA Ig 60 1.00 37.33 0.0 3495 24 MA Ig80 0.50 0.00 17.36 187500 25 MA Ig 80 0.50 9.43 0.30 7960 26 MA Ig 800.50 20.73 0.21 3860 27 MA Ig 80 0.50 38.79 0.12 2560 28 MA Ih 60 1.000.00 20.5 926632 29 MA Ih 60 1.00 6.54 22.6 66231 30 MA Ih 60 1.00 13.3027.5 37180 31 MA Ih 60 1.00 26.50 12.9 21243 32 MA Ih 80 0.50 0.00 40.6176925 33 MA Ih 80 0.50 6.91 38.3 48525 34 MA Ih 80 0.50 13.30 32.126285 35 MA Ih 80 0.50 26.50 28.4 16074 36 MA Ii 60 1.00 0.00 23.4739090 37 MA Ii 60 1.00 7.49 3.2 151740 38 MA Ii 60 1.00 14.29 1.7 9812039 MA Ii 60 1.00 29.24 0.2 52940 40 MA Ii 90 0.50 0.00 55.6 83145 41 MAIi 90 0.50 6.93 20.9 46055 42 MA Ii 90 0.50 14.91 16.4 28680 43 MA Ii 900.50 28.99 14.9 18100

Example 4: Polymerization of Vinyl Acetate

[0086] Polymerizations of vinyl acetate (VAc) were carried out in vacuoat 60° C. for one hour or at 80° C. for one hour using the followingprocedure. α,α′-Azobisisobutyronitrile (20.5 mg) was dissolved infreshly distilled vinyl acetate (25 mL). Aliquots (4 mL) were removedand added to ampoules containing weighed amounts of the chain transferagents. After the polymerization, the volatiles were removed and thepolymers were dried and examined as before. TABLE 4 Molecular Weightsand Conversions for Vinyl Acetate Polymerizations Carried Out in thePresence of Chain Transfer Agents (CTA) Temp. Time 10³[CTA]/ % Entry CTA(° C.) (hr.) [Monomer] Conv. M_(n) ^(#) 1 Ie 80 1.00 0.00 60.2 62700 2Ie 80 1.00 1.87 29.9 54700 3 Ie 80 1.00 3.72 18.9 38300 4 Ie 80 1.007.43 12.6 25900 5 Ig 60 1.00 0.00 5.37 193500 6 Ig 60 1.00 12.90 0.088200 7 Ig 60 1.00 23.90 0.02 5740 8 Ig 60 1.00 39.10 0.03 3260

[0087] Table 5 summarizes the results of chain transfer constants inpolymerizations of common monomers using the allylic chain transferagents [(Ia), (Ib), (Ic), (Ie), (If), (Ig) and (Ih)]. TABLE 5 ChainTransfer Constants (C_(x)) for Polymerizations of Common Monomers in thePresence of Allylic Transfer Agents and MMA Dimer Chain TransferConstants CTA Monomer Conditions (C_(x)) Ia MMA 60° C. 0.004 MA 80° C.0.020 Sty 60° C. 0.004 Ib MMA 60° C. 0.015 Sty 60° C. 0.148 EA 60° C.0.203 MMA EMA 60° C. 0.007 Dimer EA 60° C. 0.120 Sty 60° C. 0.057 Ic MMA60° C. 0.004 Ie VAc 80° C. 0.274 MA 60° C. 0.005 If MMA 60° C. 0.060 MA60° C. 0.450 MA 80° C. 0.560 Ig MMA 60° C. 0.040 MA 60° C. 0.670 MA 80°C. 0.850 VAc 60° C. 7.010 Ih MA 60° C. 0.150 MA 80° C. 0.180 Sty 60° C.0.150 Ii MMA 60° C. 0.029 MA 60° C. 0.053 MA 90° C. 0.130 Sty 60° C.0.009

Example 5: Polymerization of Styrene

[0088] A multi-necked reactor was equipped with a stirrer, thermocouple,and condensor. The reactor was held under nitrogen positive pressure andthe following ingredients were used. Part 1 Styrene  2 ml MEK  4 mlTransfer agent (Ib) 370 mg Part 2 Styrene  8 ml MEK  12 ml Part 3 AIBN 14 mg MEK  2 ml Part 4 MEK  2 ml

[0089] Part 1 was charged to the reactor and heated to 80° C. When thetemperature stabilized at 80° C., part 2 (the monomer feed) was chargedto the reactor concurrently with part 3 (the initiator feed) over 90minutes via a syringe pump. Then part 4 was charged to the reactor as asingle shot feed to rinse the syringe pump and the reaction mixture washeld at 80° C. for further 120 minutes. The solvent and unreactedmonomer were then distilled off. The result is summarized in Table 6.TABLE 6 CTA(Ib) M_(n) M_(w) Dispersity Control 0 20400 39350 1.93Example 5 370 mg 14900 29600 1.94

Examples 6-8: Polymerization of n-Butyl Methacrylate/HydroxypropylAcrylate

[0090] A multi-necked reactor was equipped with a stirrer, thermocouple,and condenser. The reactor was held under nitrogen positive pressure andfollowing ingredients were used in three separate polymerizations. PARTINGREDIENTS Example 6 Example 7 Example 8 I. Xylene 20.94 g 20.94 g20.94 g Transfer Agent Ib 0.00 g 3.47 g 6.94 g II. n-BMA 51.17 g 47.70 g44.23 g HPA 18.23 g 18.23 g 18.23 g III. Xylene 9.07 g 9.07 g 9.07 gVAZO 67 0.60 g 0.60 g 0.60 g

[0091] Part I was charged to the reactor and heated to 90 C. When thetemperature stabilized, Part II was charged to the reactor concurrentlywith Part III over 240 and 260 minutes, respectively. The reactionmixture was held for 60 minutes following the completion of the feedingof Part III. The monomer conversion was determined by solids analysisand molecular weight was determined by GPC. The results are summarizedin Table 7. TABLE 7 Example Wt % Number CTA(Ib) Mn Mw DispersityConversion 6 0 27180 65950 2.43 100% (control) 7 5.0% 16410 37940 2.3198% 8 10.0% 12730 26750 2.10 100%

1. A process for the free radical initiated polymerization ofunsaturated species characterised by the use of compounds of Formula (I)as chain transfer agents.

wherein X is selected from hydrogen; CN; optionally substituted aryl;COOH; COOR; C(O)NHR⁶; C(O)NR⁷R⁸; and halogen; Q is selected from COOR¹;CN; and C(O)NR⁷R⁸; Y is selected from hydrogen; C₁ to C₆ alkyl; C₁ to C₆alkyl substituted with one or more substituents selected from hydroxy,amino, C₁ to C₆ alkoxy, C₁ to C₆ alkoxycarbonyl, halogen, CN andoptionally substituted aryl; C₁ to C₆ alkenyl; and C₁ to C₆ alkynyl; Zis selected from COOR²; CN; and optionally substituted aryl; R³ and R⁴may be the same or different and are selected from hydrogen, C₁ to C₄alkyl and halogen; or R³ and R⁴ together with the carbon atom to whichthey are attached form part of a carbocyclic or heterocyclic ringstructure; R is selected from C₁ to C₁₈ alkyl; C₁ to C₁₂ alkylsubstituted with one or more substituents selected from hydroxy, amino,C₁ to C₆ alkoxy, phenyl, halogen, NCO, CN, and COOR⁵; R¹ and R² may bethe same or different and are selected from C₁ to C₁₈ alkyl; C₁ to C₁₂alkyl substituted with one or more substituents selected from hydroxy,C₁ to C₆ acyloxy, C₁ to C₆ alkoxy, amino, halogen, Si(R⁹)₃, Si(OR⁹)₃,optionally substituted aryl, CN and NCO; R⁵ is selected from hydrogenand C₁ to C₆ alkyl; R⁶ is selected from hydrogen and C₁ to C₁₈ alkyl; R⁷and R⁸ may be the same or different and are selected from C₁ to C₁₈alkyl; and R⁹ is selected from C₁ to C₁₈ alkyl; C₁ to C₁₈ cycloalkyl;and optionally substituted aryl.
 2. The process of claim 1 wherein X isa phenyl, substituted phenyl, chloro or bromo group.
 3. The process ofclaim 1 wherein Y is a phenyl or substituted phenyl.
 4. The process ofclaim 1 wherein R¹ and R⁴ may be the same or different and are a chloroor fluoro group.
 5. The process of claim 1 wherein compounds of Formula(IA) are used as chain transfer agents.

wherein Y, R, R⁶, R⁷ and R⁸ are as defined in claim 1; X is selectedfrom hydrogen; CN; optionally substituted aryl; COOH; COOR; C(O)NHR⁶;C(O)NR⁷R⁸; and halogen; Y is selected from hydrogen; C₁ to C₆ alkyl; C₁to C₆ alkyl substituted with one or more substituents selected fromhydroxy, amino, C₁ to C₆ alkoxy, C₁ to C₆ alkoxycarbonyl, halogen, CN,optionally substituted aryl; C₁ to C₆ alkenyl; and C₁ to C₆ alkynyl; R¹and R² may be the same or different and are selected from C₁ to C₁₈alkyl; C₁ to C₁₂ alkyl substituted with a substituent selected fromhydroxy, C₁ to C₆ acyloxy, C₁ to C₆ alkoxy, amino, halogen, optionallysubstituted aryl, CN and NCO; and R³ and R⁴ may be the same or differentand are selected from hydrogen; C₁ to C₄ alkyl; and halogen.
 6. Theprocess of claim 5 wherein X is a phenyl, substituted phenyl, chloro orbromo group.
 7. The process of claim 5 wherein Y is a phenyl orsubstituted phenyl.
 8. The process of claim 5 wherein R³ and R⁴ may bethe same or different and are hydrogen, chloro or fluoro groups.
 9. Theprocess of claim 1 wherein compounds of Formula (IB) are used as chaintransfer agents:

wherein X, Y, R¹, R³ and R⁴ are as defined in claim 1; and Z isoptionally substituted aryl.
 10. The process of any one of claims 1 to 9where the polymerisation occurs in solution.
 11. The process of any oneof claims 1 to 9 where the polymerisation occurs in an emulsified phase.12. The process of any one of claims 1 to 9 when the unsaturated speciesare added before the polymerisation commences.
 13. The process of anyone of claims 1 to 9 when the unsaturated species are added during thereaction.
 14. The process of of any one of claims 1 to 9 when part ofthe unsaturated species are added before the start of the reaction andthe remainder of the unsaturated species are added during the reaction.15. A polymer made by the process of any one of claims 1 to
 14. 16. Acompound of Formula (I) as defined in claim 1 which is selected from:ethyl 2,4-bis(ethoxycarbonyl)-2-methyl-4-pentenoate; ethyl2,4-bis(ethoxycarbonyl)-2-ethyl-4-pentenoate; ethyl2-benzyl-2,4-bis(ethoxycarbonyl)-4-pentenoate; ethyl2-ethoxycarbonyl-2-methyl-4-phenyl-4-pentenoate; ethyl2-ethoxycarbonyl-2,3-dimethyl-4-(t-butoxycarbonyl)-4-pentenoate; andethyl 2-phenyl-4-(t-butoxycarbonyl)-4-pentenoate.
 17. A compound ofFormula (I) as defined in any one of claims 1, 5, 9 and 16 for use as achain transfer agent in the free radical initiated polymerisation ofunsaturated species.
 18. A chain transfer agent for use in the freeradical initiated polymerisation of unsaturated species which comprisesa compound of Formula (I) as defined in any one of claims 1, 5, 9 and16.
 19. Use as a chain transfer agent in the free radical initiatedpolymerisation of unsaturated species of a compound of Formula (I) asdefined in any one of claims 1, 5, 9 and 16.